POLISHING PAD WITH IMPROVED WETTABILITY AND METHOD FOR PREPARING SAME
The present invention discloses a polishing pad comprising a laminate composed of a polishing layer, an adhesive layer, and a cushion layer, wherein the cushion layer has a water absorption rate of 100% or less, and a process for manufacturing the polishing pad.
1 . A polishing pad, which comprises a laminate composed of a polishing layer, an adhesive layer, and a cushion layer, wherein the cushion layer has a water absorption rate of 100% or less according to the following Equation (1):
Water
absorption
rate
(
%
)
=
W
2
-
W
1
W
1
×
100
Equation
(
1
)
in Equation (1), W1 is the weight (g) of a specimen obtained by cutting the cushion layer to 35 mm in length and in width, and W2 is the weight (g) of the specimen measured after it is immersed in water for 24 hours.
2 . The polishing pad of claim 1 , wherein the cushion layer comprises a base layer,
the base layer comprises a surface coating layer formed from a coating composition comprising a fluorine-based resin or a silane-based resin, or
the base layer is impregnated with an impregnation composition comprising a fluorine-based resin or a silane-based resin.
3 . The polishing pad of claim 2 , wherein the surface coating layer has a thickness of 80 μm to 120 μm.
4 . The polishing pad of claim 2 , wherein the base layer is a nonwoven fabric comprising at least one resin selected from the group consisting of a polyester resin, a polyamide resin, a polyurethane resin, a polyolefin resin, and a fluoropolymer resin, and
the base layer has a thickness of 0.5 mm to 2.5 mm.
5 . The polishing pad of claim 1 , wherein the cushion layer has a contact angle of 76° to 90°.
6 . The polishing pad of claim 1 , wherein the cushion layer has a dry compressibility of 3% to 15% according to the following Equation (2):
Dry
compressibility
(
%
)
=
D
1
-
D
2
D
1
×
100
Equation
(
2
)
in Equation (2), D1 and D2 are the thickness (pm) of a specimen obtained by cutting the cushion layer to a size of 25 mm in length and in width when measured after an adhesive tape is attached to the upper and lower sides of the specimen, which is then pressed for 30 seconds with a weight of 85 g and further pressed for 3 minutes with an additional weight of 800 g, respectively.
7 . The polishing pad of claim 6 , wherein the cushion layer has a dry compressive elasticity of 55% or less according to the following Equation (4):
Dry
compressive
elasticity
(
%
)
=
D
5
-
D
2
D
1
-
D
2
×
100
Equation
(
4
)
in Equation (4), D5 is the thickness (pm) of a specimen obtained by cutting the cushion layer to a size of 25 mm in length and in width when measured after an adhesive tape is attached to the upper and lower sides of the specimen, which is then pressed for 30 seconds with a weight of 85 g, further pressed for 3 minutes with an additional weight of 800 g, and left for 1 minute after the weight of 800 g is removed.
8 . The polishing pad of claim 1 , wherein the cushion layer has a wet compressibility of 5.0% to 6.6% according to the following Equation (3):
Wet
compressibility
(
%
)
=
D
3
-
D
4
D
3
×
100
Equation
(
3
)
in Equation (3), D3 and D4 are the thickness (μm) of a specimen obtained by cutting the cushion layer to a size of 25 mm in length and in width when measured after an adhesive tape is attached to the upper and lower sides of the specimen, which is then immersed in water for 24 hours, pressed for 30 seconds with a weight of 85 g, and further pressed for 3 minutes with an additional weight of 800 g, respectively.
9 . The polishing pad of claim 8 , wherein the cushion layer has a wet compressive elasticity of 60% or less according to the following Equation (5):
Wet
compressive
elasticity
(
%
)
=
D
6
-
D
4
D
3
-
D
4
×
100
Equation
(
5
)
in Equation (5), D6 is the thickness (μm) of a specimen obtained by cutting the cushion layer to a size of 25 mm in length and in width when measured after an adhesive tape is attached to the upper and lower sides of the specimen, which is immersed in water for 24 hours and then pressed for 30 seconds with a weight of 85 g, further pressed for 3 minutes with an additional weight of 800 g, and left for 1 minute after the weight of 800 g is removed.
10 . The polishing pad of claim 1 , wherein the polishing pad has a within-wafer non-uniformity of 3.5% or less.
11 . The polishing pad of claim 1 , wherein the interfacial adhesion between the polishing layer and the cushion layer is 6.0 kgf/25 mm to 7.7 kgf/25 mm.